The proposed research will examine the neurotoxic effects of low-level lead exposure following early postnatal development. Emphasis will be placed on a functional analysis of the various components of the visual system. Functional analysis of the visual capacities at scotopic and photopic levels of luminance, such as sensitivity to light, temporal resolution and spatial resolution, will be studied directly by electrophysiological techniques and indirectly by behavioral (psychophysical) measures. This will be done utilizing well-documented techniques that have previously been used to yield reliable psychophysical data in electrophysiological and behavioral experiments on man and animals. The functional bioelectric properties of the visual pathways that preferentially transmit the temporal and spatial information of the visual system will also be examined using electrophysiological techniques. In addition, analytical determinations of lead and zinc (and copper and iron) will be carried out in the retina and other visual system structures to determine if the visual neurotoxicity of lead is the result of a competitive displacement of zinc. The experiments outlined in the proposal will allow us to determine the site(s) of action and mechanism(s) of action responsible for the decreased visual capacities preferentially observed at scotopic levels of luminance following developmental lead exposure.